Cycloalkylaminomethylpyrrolidine derivatives

ABSTRACT

A quinolone derivative represented by formula (I):                    
     wherein R 1  represents a cycloalkyl group; R 2  represents a hydrogen atom, an amino group, a hydroxyl group, a thiol group, a halogenomethyl group, an alkyl group, an alkenyl group, an alkynyl group, or an alkoxyl group; R 3  represents an amino group, a halogenomethyl group, a halogenomethoxyl group, an alkyl group, an alkenyl group, an alkynyl group, or an alkoxyl group; R 4  represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R 5  represents a cycloalkyl group having 3 to 6 carbon atoms; the above R 1  to R 5  may be substituted; X represents a halogen atom or a hydrogen atom; and Y represents a hydrogen atom, a phenyl group, an acetoxymethyl group, a pivaloyloxymethyl group, an ethoxycarbonyl group, a choline group, a dimethylaminoethyl group, a 5-indanyl group, a phthalidinyl group, a 5-alkyl-2-oxo-1,3-dioxol-4-ylmethyl group, a 3-acetoxy-2-oxobutyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxymethyl group having 2 to 7 carbon atoms, or a phenylalkyl group having 1 to 6 carbon atoms in the alkyl moiety thereof, or a salt thereof. The compound exhibits high and broad antimicrobial activity against various bacteria including bacteria resistant to drugs and high safety.

TECHNICAL FIELD

This invention relates to an antimicrobial compound useful as a drug forhumans, animals or fishes or an antimicrobial preservative, anantimicrobial agent or preparation containing the same, and a method fortreating and/or preventing various infectious diseases using the same.

BACKGROUND ART

Quinolone derivatives having a 3-(cyclopropyl-aminomethyl)pyrrolidinylgroup are disclosed in JP-A-59-67269 (the term “JP-A” as used hereinmeans an “unexamined published Japanese patent application”), but aquinolone derivative according to the present invention which has asubstituent derived from the cycloalkylaminomethylpyrrolidine compoundat the 7-position and a substituent other than a halogen atom at the8-position and may also have a substituent at the 5-position is unknown.

Recently, many synthetic quinolone antimicrobial agents excellent in notonly antimicrobial activity but also in oral absorbability, distributionproperty to organ, and excretion rate have been developed and providedfor clinical use as a chemotherapeutic agent effective on variousinfectious diseases.

However, low sensitive bacteria resistant to these drugs have recentlybeen increasing in the medicinal field. Further, bacteria resistant todrugs other than quinolone antimicrobial agents have also been acquiringresistance to quinolone antimicrobial agents, as β-lactam resistantStaphylococcus aureaus (MRSA). Therefore more effective drugs have beenkeenly demanded in the field of medicine.

The antimicrobial activity, efficacy and safety of quinoloneantimicrobial agents are largely influenced by the substituents at the7- and 1-positions. And at the same time, the substituents at the 5- and8-positions also have considerable role to those features. The inventorsof the present invention have considered that proper assortment ofproper substituents to these positions could provide compounds excellentin antimicrobial activity, efficacy and safety. They have extensivelystudied seeking a compound exhibiting high antimicrobial activity on abroad range of bacteria including quinolone-resistant bacteria. As aresult, it has been found that a quinolone compound having a substituentderived from a cycloalkylaminomethylpyrrolidine compound at the7-position and having a substituent other than a halogen atom at the8-position exhibits potent antimicrobial activity toward Gram negativebacteria and Gram positive bacteria, especially Gram positive bacteriaincluding MRSA. It has also been found that the compound additionallyhaving a substituent at the 5-position shows similarly excellentantimicrobial activity.

It has further been found that the compound having a halogenocyclopropylgroup, particularly a fluorocyclopropyl group, at the 1-position isexcellent in efficacy and safety as well as antimicrobial activity. Thepresent invention has been completed based on these findings.

Of the quinolone derivatives of the present invention having asubstituted cyclic alkyl group, e.g., a halogenocyclopropyl group, atthe 1-position, a pair of enantiomers attributed only to thehalogenocyclopropane ring are present even when there is nostereoisomerism in the substituent at the other position. This isascribed to the steric relationship between the pyridonecarboxylic acidmoiety and the halogen atom on the cyclopropane ring. It is possible toapply a racemic mixture of the enantiomers as a drug as such.

Where stereoisomerism exists at other position in addition to thehalogenocyclopropane moiety, particularly at the 7-positionedsubstituent, such a quinolone derivative embraces diastereomers, thatis, at least 4 kinds of stereoisomers are possible. A mixture ofdiastereomers is a mixture of isomers having different physicalproperties and is hardly applicable as a drug as such.

The present inventors have made an effort to obtain a quinolone compoundas a pure stereoisomer even if there are diastereomers, particularly apure stereoisomer of 1-(1,2-cis-2-fluorocyclopropyl)-substitutedquinolone derivative.

As a result, the present inventors have succeeded in separatelyobtaining each enantiomer of cis-2-fluorocyclopropylamine as a pureisomer. Starting with this cis-fluorocyclopropylamine, they separatelyobtained each enantiomer of a quinolone derivative attributed only tothe steric configuration of the fluorocyclopropane ring thereof. Theyalso succeeded in obtaining each enantiomer of acycloalkylaminomethylpyrrolidine compound having an asymmetric carbonatom as a pure isomer.

Now that the above-mentioned quinolone derivative andcycloalkylaminomehylpyrrolidine compound useful as an intermediate havebeen obtained, it is possible to synthesize an optically activequinolone derivative substantially comprising a pure diastereomer.

DISCLOSURE OF INVENTION

The present invention relates to a compound represented by formula (I):

wherein R¹ represents a substituted or unsubstituted cyclic alkyl grouphaving 3 to 6 carbon atoms;

R² represents a hydrogen atom, an amino group, a hydroxyl group, a thiolgroup, a halogenomethyl group, an alkyl group having 1 to 6 carbonatoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl grouphaving 2 to 6 carbon atoms, or an alkoxyl group having 1 to 6 carbonatoms, and said amino group may have at least one substituent selectedfrom a group of a formyl group, an alkyl group having 1 to 6 carbonatoms and an acyl group having 2 to 5 carbon atoms;

R³ represents an amino group, a halogenomethyl group, a halogenomethoxylgroup, an alkyl group having 1 to 6 carbon atoms, an alkenyl grouphaving 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms,or an alkoxyl group having 1 to 6 carbon atoms, and said amino group mayhave at least one substituent selected from a group of a formyl group,an alkyl group having 1 to 6 carbon atoms and an acyl group having 2 to6 carbon atoms;

R⁴ represents a hydrogen atom or an alkyl group having 1 to 6 carbonatoms, and said alkyl group may have at least one substituent selectedfrom a group of a hydroxyl group, a halogen atom, an alkylthio grouphaving 1 to 6 carbon atoms and an alkyloxyl group having 1 to 6 carbonatoms;

R⁵ represents a cyclic alkyl group having 3 to 6 carbon atoms;

X represents a halogen atom or a hydrogen atom; and

Y represents a hydrogen atom, a phenyl group, an acetoxymethyl group, apivaloyloxymethyl group, an ethoxycarbonyl group, a choline group, adimethylaminoethyl group, a 5-indanyl group, a phthalidinyl group, a5-alkyl-2-oxo-1,3-dioxol-4-ylmethyl group, a 3-acetoxy-2-oxobutyl group,an alkyl group having 1 to 6 carbon atoms, an alkoxymethyl group having2 to 7 carbon atoms, or a phenylalkyl group having 1 to 6 carbon atomsin the alkyl moiety thereof, and a salt thereof.

Further, the present invention relates to the followings:

the compound of formula (I), wherein R¹ is a 2-halogenocyclopropylgroup, and a salt thereof;

the compound of formula (I), wherein R¹ is a1,2-cis-2-halogenocyclopropyl group, and a salt thereof;

the compound of formula (I), wherein R¹ is a substantiallystereochemically pure substituent, and a salt thereof;

the compound of formula (I), wherein R¹ is a(1R,2S)-2-halogenocyclopropyl group, and a salt thereof;

the compound of formula (I), wherein R¹ is a fluorocyclopropyl group,and a salt thereof;

the compound of formula (I), wherein the compound is a substantiallystereochemically pure compound, and a salt thereof;

an antimicrobial agent and/or preparation containing the compound offormula (I) or a salt thereof as an active ingredient; and

a method for treating and/or preventing an infectious disease by usingthe compound of formula (I) or a salt thereof.

EMBODIMENTS OF INVENTION

The substituents disclosed in the formula (I) of the present inventionare explained below.

The substituent R¹ represents a substituted or unsubstituted cyclicalkyl group having 3 to 6 carbon atoms. The cyclic alkyl group ispreferably a cyclopropyl group. The substituent of the substitutedcyclic alkyl group is preferably a halogen atom, particularly a fluorineatom. Where R¹ is a halogenocyclopropyl group, the halogen atom and thepyridonecarboxylic acid moiety are preferably in a cis-configurationwith respect to the cyclopropane ring.

The substituent R² represents a hydrogen atom, an amino group, ahydroxyl group, a thiol group, a halogenomethyl group, an alkyl grouphaving 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms,an alkynyl group having 2 to 6 carbon atoms, or an alkoxyl group having1 to 6 carbon atoms, and said amino group may have at least onesubstituent selected from a group of a formyl group, an alkyl grouphaving 1 to 6 carbon atoms and an acyl group having 2 to 5 carbon atoms.

The alkyl group as R² can be straight or branched of from 1 to 6 carbonatoms and preferably includes a methyl group, an ethyl group, ann-propyl group, and an isopropyl group. The alkenyl group as R² can bestraight or branched of from 2 to 6 carbon atoms and is preferably avinyl group. The alkynyl group as R² can be straight or branched of from2 to 6 carbon atoms and is preferably an ethynyl group. The halogen atomof halogenomethyl group as R² is preferably a fluorine atom and thenumber of the halogen atom is from 1 to 3. The alkoxyl group as R² canbe of from 1 to 6 carbon atoms and is preferably a methoxyl group.

The substituent R³ represents an amino group, a halogenomethyl group, ahalogenomethoxyl group, an alkyl group having 1 to 6 carbon atoms, analkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6carbon atoms, or an alkoxyl group having 1 to 6 carbon atoms, and saidamino group may have at least one substituent selected from a group of aformyl group, an alkyl group having 1 to 6 carbon atoms and an acylgroup having 2 to 6 carbon atoms.

The alkyl group as R³ can be straight or branched of from 1 to 6 carbonatoms and is preferably a methyl group or an ethyl group. The alkenylgroup as R³ can be straight or branched of from 2 to 6 carbon atoms andis preferably a vinyl group. The alkynyl group as R³ can be straight orbranched of from 2 to 6 carbon atoms and is preferably an ethynyl group.The halogen atom of halogenomethyl group as R³ is preferably a fluorineatom and the number of the halogen atom is from 1 to 3. The alkoxylgroup as R³ is preferably a methoxyl group. The halogen atom ofhalogenomethoxyl group as R³ is preferably a fluorine atom and thenumber of the halogen atom is from 1 to 3.

The substituent R⁴ represents a hydrogen atom or an alkyl group having 1to 6 carbon atoms, and said alkyl group may have at least onesubstituent selected from a group of a hydroxyl group, a halogen atom,an alkylthio group having 1 to 6 carbon atoms and an alkyloxy grouphaving 1 to 6 carbon atoms.

The alkyl group as R⁴ can be straight or branched of from 1 to 6 carbonatoms and preferably includes a methyl group, an ethyl group, ann-propyl group, and an isopropyl group. The hydroxyl-substituted alkylgroup as R⁴ can be straight or branched of from 1 to 6 carbon atoms andis preferably a hydroxyethyl group or a hydroxypropyl group.

The substituent R⁵ represents a cyclic alkyl group having 3 to 6 carbonatoms, preferably a cyclopropyl group or a cyclobutyl group.

The substituent X represents a halogen atom or a hydrogen atom. Thehalogen atom as X is preferably a fluorine atom.

The substituent Y represents a hydrogen atom, a phenyl group, anacetoxymethyl group, a pivaloyloxymethyl group, an ethoxycarbonyl group,a choline group, a dimethylaminoethyl group, a 5-indanyl group, aphth~alidinyl group, a 5-alkyl-2-oxo-1,3-dioxol-4-ylmethyl group, a3-acetoxy-2-oxobutyl group, an alkyl group having 1 to 6 carbon atoms,an alkoxymethyl group having 2 to 7 carbon atoms, or a phenylalkyl grouphaving 1 to 6 carbon atoms in the alkyl moiety thereof.

Where R² or R³ is an amino group, a hydroxyl group or a thiol group, itmay be protected with a protective group used in this field.

Examples of such protective groups include an alkoxycarbonyl group,e.g., a t-butoxycarbonyl group, a 2,2,2-trichloroethoxycarbonyl group;an aralkyloxycarbonyl group, e.g., a benzyloxycarbonyl group, ap-methoxybenzyloxycarbonyl group, and a p-nitrobenzyloxycarbonyl group;an acyl group, e.g., an acetyl group, a methoxyacetyl group, atrifluoroacetyl group, a chloroacetyl group, a pivaloyl group, a formyylgroup, and a benzoyl group; an alkyl or aralkyl group, e.g., a t-butylgroup, a benzyl group, a p-nitrobenzyl group, a p-methoxybenzyl group,and a triphenylmethyl group; an ether group, e.g., a methoxymethylgroup, a t-butoxymethyl group, a tetrahydropyranyl group, and a2,2,2-trichloroethoxymethyl group; and a silyl group, e.g., atrimethylsilyl group, an isopropyldimethylsilyl group, at-butyldimethylsilyl group, a tribenzylsilyl group, and at-butyldiphenylsilyl group. The compound of the invention having suchprotected substituents are particularly useful as an intermediate.

A preferable assortment of R² and R³ in the compound of formula (I) isas follows: R² is an amino group, a hydrogen atom, a hydroxyl group oran alkyl group having 1 to 6 carbon atoms while R³ is an alkyl grouphaving 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atomsor a halogenomethoxyl group.

It is still preferred that R² is an amino group, a hydrogen atom, ahydroxyl group or a methyl group while R³ is a methyl group, a methoxylgroup or a difluoromethoxyl group.

Where R² and R³ are selected from the above assortments, X is preferablya fluorine atom.

The compound of formula (I) in which R¹ is a halogenocyclopropyl groupwill be described in detail.

The halogen atom on the cyclopropyl group includes a fluorine atom and achlorine atom, with a fluorine atom being particularly preferred. Thehalogen atom and the pyridonecarboxylic acid moiety are preferably in acis-configuration with respect to the cyclopropane ring. Regardless ofstereoisomerism of the 7-positioned substituent, the 1-positionedcis-2-halogenocyclopropyl moiety makes a pair of enantiomers, each ofwhich was observed to exhibit potent antimicrobial activity and highsafety.

Where the compound of formula (I) has such a structure that containsdiastereomers, it is preferable to administer to humans or animals acompound substantially comprising a pure diastereomer. The term “acompound substantially comprising a pure diastereomer” as used herein isconstrued as including not only a compound containing no otherdiastereomer but a compound containing other diastereomers to such anextent that the compound is recognized to be stereochemically pure as awhole. In other words, it is construed as meaning that otherdiastereomers may exist to some extent as long as the existence gives nosubstantial influence on physiological activities or physicochemicalconstants.

The term “substantially stereochemically pure” as used herein isintended to mean that a compound substantially comprising a singlesteric isomer of the compound ascribed to its asymmetric carbon atom.The latitude of the term “pure” in “pure diastereomer” also applieshere.

The pyridonecarboxylic acid derivative of the present invention may haveeither a free form or a form of an acid addition salt or a carboxylicacid salt. Acid addition salts include inorganic acid salts, such ashydrochlorides, sulfates, nitrates, hydrobromides, hydroiodides, andphosphates; and organic acid salts, such as acetates, methanesulfonates,benzenesulfonates, toluenesulfonates, citrates, maleates, fumarates, andlactates.

The carboxylic acid salts include both inorganic salts and organicsalts, such as alkali metal salts, e.g., lithium salts, sodium salts,and potassium salts; alkaline earth metal salts, e.g., magnesium saltsand calcium salts; ammonium salts; triethylamine salts,N-methylglucamine salts, and tris-(hydroxymethyl)aminomethane salts.

The free pyridonecarboxylic acid derivatives, acid addition saltsthereof, and carboxylic acid salts thereof may be present as a hydrate.

On the other hand, quinolone derivatives with the carboxylic acid moietythereof having an ester form are useful as a synthetic intermediate or apro-drug (a drug precursor). For example, alkyl esters, benzyl esters,alkoxyalkyl esters, phenylalkyl esters, and phenyl esters are useful assynthetic intermediates.

Esters which can be used as pro-drugs are esters which are easilycleaved in vivo to produce a free carboxylic acid, includingacetoxymethyl esters, pivaloyloxymethyl esters, ethoxycarbonyl esters,choline esters, dimethylaminoethyl esters, 5-indanyl esters,phthalidinyl esters, 5-alkyl-2-oxo-1,3-dioxol-4-ylmethyl esters, andoxoalkyl esters, such as 3-acetoxy-2-oxobutyl esters.

The compound of formula (I) can be prepared through various processes. Apreferred process comprises reacting a compound represented by formula(II):

wherein R¹, R², R³, and X are as defined above; A represents asubstituent serves as a leaving group, such as a fluorine atom, achlorine atom, a bromine atom, an alkylsulfonyl group having 1 to 3carbon atoms or an arylsulfonyl group (e.g., a benzenesulfonyl group ora toluenesulfonyl group); and Y has the same meaning as Y in formula (I)and additionally represents a substituent of formula (III):

wherein R¹¹ and R¹² each represent a fluorine atom or a loweralkylcarbonyloxy group, with a compound represented by formula (IV):

wherein R⁴ has the same meaning as R⁴ in formula (I) and additionallyrepresents a nitrogen protective group Rx; and R⁵ is as defined above,or an acid addition salt thereof.

The nitrogen protective group Rx are those ordinary used in this field.Examples of Rx are; an alkyloxycarbonyl group, e.g., a t-butoxycarbonylgroup and a 2,2,2-trichloroethoxycarbonyl group; an aralkyloxycarbonylgroup, e.g., a benzyloxycarbonyl group, a paramethoxybenzyloxycarbonylgroup, and a paranitrobenzyloxycarbonyl group; an acyl group, e.g., anacetyl group, a methoxyacetyl group, a trifluoroacetyl group, achloroacetyl group, a pivaloyl group, a formyl group, and a benzoylgroup; an alkyl group or an aralkyl group, e.g., a t-butyl group, abenzyl group, a paranitrobenzyl group, a paramethoxybenzyl group, and atriphenylmethyl group; an ether group, e.g., a methoxymethyl group, at-butoxymethyl group, a tetrahydropyranyl group, and a2,2,2-trichloroethoxymethyl group; and a silyl group, e.g., atrimethylsilyl group, an isopropyldimethylsilyl group, at-butyldimethylsilyl group, a tribenzylsilyl group, and at-butyldiphenylsilyl group.

The resulting compound in which Y is an alkyl group having 1 to 6 carbonatoms, an alkoxymethyl group having 2 to 7 carbon atoms or a phenylalkylgroup having 1 to 6 carbon atoms in the alkyl moiety thereof can beconverted to the corresponding carboxylic acid by hydrolysis under anacidic or basic condition commonly used for hydrolysis of carboxylicesters. The protective group, if any, is removed under properly selectedconditions to obtain a desired compound (I).

The compound obtained by the substitution reaction between the compound(II) wherein Y is the group (III) and the compound (IV) can be convertedto the corresponding carboxylic acid by treatment with an acidic orbasic compound.

The substitution reaction between the compounds (II) and (IV) is carriedout with or without a solvent. The solvent, if used, is not limited aslong as it is inert under the reaction conditions. Suitable solventsinclude dimethyl sulfoxide, pyridine, acetonitrile, ethanol, chloroform,dimethylformamide, dimethylacetamide, N-methylpyrrolidone,tetrahydrofuran, water, and 3-methoxybutanol. These solvents may be usedas a mixture thereof.

The reaction is usually performed within the range of room temperatureto 200° C., preferably 25 to 150° C., for 0.5 to 48 hours. The reactionusually completes in about 0.5 to 2 hours. It is advantageous to conductthe reaction in the presence of an acid acceptor, such as an inorganicbase (e.g., an alkali metal or alkaline metal carbonate orhydrogencarbonate) or an organic base (e.g., triethylamine or pyridine).

The optically active cis-2-fluorocyclopropylamine, which substantiallycomprises a-pure isomer and is preferred as a starting compound for thesynthesis of the compound (I) substantially comprising a pure isomer,can be synthesized by, for example, the process described inJP-A-2-231475. The thus obtained cis-2-fluorocyclopropylamine derivativeis led to the compound of formula (II) substantially comprising a pureisomer by, for example, the process described in JP-A-2-231475.

The compounds of the present invention have potent antimicrobialactivity and are therefore useful as drugs for humans, animals orfishes, agricultural chemicals, or food preservatives.

For use as drugs for humans, the dose of the compound is in the range offrom 50 mg to 1 g, and preferably from 100 mg to 300 mg, per day foradults.

For veterinary use, the dose is generally in the range of from 1 to 200mg, and preferably from 5 to 100 mg, per kg of body weight per day whilevarying depending on the purpose of administration (e.g., for therapy orfor prevention), etc., the kind and the size of the animal, the kind ofthe pathogenic organisms, and severity of symptom.

The above-mentioned daily dose is given once a day or in 2 to 4 divideddoses. If necessary, a daily dose may exceed the above-specified range.

The compounds according to the present invention are active on a broadrange of microorganisms causing various infectious diseases andeffective to prevent, alleviate or cure diseases caused by thesepathogenes. Examples of bacteria or bacterium-like microorganisms onwhich the compounds of the invention are effective includeStaphylococci, Streptococcus pyogenes, Streptococcus haemolyticus,Streptococcus fecalis, Streptococcus pneumoniae, Peptostreptococci,Neisseria gonorrhoeae, Escherichia coli, Citrobacter sp., Shigella sp.,Klebsiella pneumoniae, Enterobacter sp., Serratia sp., Proteus sp.,Pseudomonas aeruginosa, Haemophilus influenzae, Acinetobacter sp.,Campylobacter sp., and Chlamydozoon trachomatis.

Diseases which are caused by these pathogenes include folliculitis,furuncle, carbuncle, erysipelas, phlegmon, lymphangitis/lymphadenitis,felon, subcutaneous abscess, spiradenitis, acne agminata, infectiousatheroma, perianal abscess, mastadenitis, superficial secondaryinfections after trauma, burn or surgery trauma, pharyngolaryngitis,acute bronchitis, tonsillitis, chronic bronchitis, bronchiectasis,diffuse panbronchiolitis, secondary infections of chronic respiratorydiseases, pneumonia, pyelonephritis, cystitis, prostatitis,epididymitis, gonococcal urethritis, non-gonococcal urethritis,cholecystitis, cholangitis, bacillary dysentery, enteritis, adnexitis,intrauterine infections, bartholinitis, blepharitis, hordeolum,dacryocystitis, tarsadenitis, keratohelcosis, otitis media, sinusitis,paradentosis, pericoronitis, gnathitis, peritonitis, endocarditis,septicemia, meningitis, and skin infections.

The compounds of the present invention are also effective on variousmicroorganisms causing veterinary diseases, such as those belonging tothe genera Escherichia, Salmonella, Pasteurella, Haemophilus,Bordetella, Staphylococcus, and Mycoplasma. Illustrative examples of theveterinary diseases include those of fowl, such as colibacillosis,pullorum disease, avian paratyphosis, fowl cholera, infectious coryza,staphylomycosis, and mycoplasmosis; those of pigs, such ascolibacillosis, salmonellosis, pasteurellosis, hemophilus infections,atrophic rhinitis, exudative epidermitis, and mycoplasmosis; those ofcattle, such as colibacillosis, salmonellosis, hemorrhagic septicemia,mycoplasmosis, bovine contagious pleuropneumonia, and bovine mastitis;those of dogs, such as colisepsis, salmonellosis, hemorrhagicsepticemia, pyometra, and cystitis; those of cats, such as exudativepleurisy, cystitis, chronic rhinitis, and hemophilus infections; andthose of kittens, such as bacterial diarrhea and mycoplasmosis.

Dosage forms of pharmaceutical preparations containing the compound ofthe present invention are appropriately selected according to theadministration route and can be prepared by conventional preparationmethods. Examples of dosage forms for oral administration includetablets, powders, granules, capsules, solutions, syrups, elixirs, andoily or aqueous suspensions.

Injectable preparations may contain adjuvants, such as stabilizers,antiseptics, and solubilizers. The injectable solution which may containthese adjuvants may be put into a container and solidified by, forexample, lyophilization to prepare a solid preparation which isdissolved on use. The container may contain either a single dose ormultiple doses.

Preparations for external application include solutions, suspensions,emulsions, ointments, gels, creams, lotions, and sprays.

Solid preparations may contain, in addition to the active compound,pharmaceutically acceptable additives. For example, the active compoundis mixed with additives selected according to necessity from amongfillers, extenders, binders, disintegrators, absorption accelerators,wetting agents, and lubricants and formulated into solid preparations.

Liquid preparations include solutions, suspensions, and emulsions. Theymay contain adjuvants, such as suspending agents, emulsifiers, and soforth.

The compound can be administered to animals orally either directly or bymixing with feedstuff, or in a dissolved form directly given to animalsor by mixing with water or feedstuff or non-orally by injection.

For veterinary use, the compound can be formulated into powders, finegranules, soluble powders, syrups, solutions, and injections accordingto the customary methods in the art.

The present invention will now be illustrated by way of FormulationExamples, Reference Examples, and Examples, but the present inventionshould not be construed as being limited thereto. All the percents areby weight unless otherwise indicated.

Formulation Example 1

Capsules Compound of Example 2 100.0 mg Corn starch  23.0 mg CMC•Ca 22.5 mg Hydroxymethyl cellulose  3.0 mg Magnesium stearate  1.5 mgTotal 150.0 mg

Formulation Example 2

Solution Compound of Example 2 1 to 10 g Acetic acid or sodium hydroxide0.5 to 2 g Ethyl p-hydroxybenzoate 0.1 g Purified water 87.9 to 98.4 gTotal 100 g

Formulation Example 3

Powder for Mixing with Feed Compound of Example 2 1 to 10 g Corn starch89.5 to 98.5 g Light anhydrous silicic acid 0.5 g Total 100 g

BEST MODE FOR CARRYING OUT INVENTION EXAMPLES Reference Example 1

(3R)-N-Cyclopropyl-1-[(R)-phenylethyl]-5-oxopyrrolidine-3-carboxamide

To a solution of 2.33 g (10 mmol) of(3R)-1-[(R)-phenylethyl]-5-oxopyrrolidine-3-carboxylic acid in 20 ml ofacetonitrile was added 1.83 g (11.5 mol) of 1,1′-carbonyldiimidazole,and the mixture was heated at 60° C. for 1 hour. The reaction mixturewas cooled, and 655 mg (11.5 mmol) of cyclopropylamine was added theretowhile cooling with ice, followed by stirring at room temperature for 19hours. The solvent was evaporated, and chloroform was added to theresidue. The mixture was washed successively with a 10% citric acidaqueous solution and water, and dried over sodium sulfate. The solventwas evaporated to give 2.56 g (94%) of the title compound.

¹H-NMR (CDCl₃) δ ppm: 0.45-0.51 (2H, m), 0.70-0.80 (2H, m), 1.53 (3H, d,J=6.84 Hz), 2.53-2.59 (1H, m), 2.67-2.83 (3H, m), 3.07-3.12 (1H, m),3.53-3.67 (1H, m), 5.44-5.49 (1H, m), 5.82 (1H, brs), 7.25-7.35 (5H, m).

Reference Example 2

(3R)-3-(N-Cyclopropylaminomethyl)-1-[(R)-phenylethyl]pyrrolidine

To a solution of 2 g (7.35 mol) of(3R)-N-cyclopropyl-1-[(R)-phenylethyl]-5-oxopyrrolidine-3-carboxamide in60 ml of tetrahydrofuran was added a 37 ml of a solution containing 1mmol of a borane-tetrahydrofuran complex under ice-cooling, and themixture was stirred at room temperature for 17 hours. The solvent wasevaporated, and chloroform was added to the residue. The mixture waswashed with a saturated sodium chloride aqueous solution and dried oversodium sulfate. The solvent was evaporated, and a 5N sodium hydroxideaqueous solution was added to the residue, followed by refluxing for 5hours. After cooling, a saturated sodium chloride aqueous solution wasadded to the reaction mixture, and the mixture was extracted withchloroform. The extract was dried over sodium sulfate, and the solventwas evaporated to give 1.63 g (91%) of the title compound.

¹H-NMR (CDCl₃) δ ppm: 0.27-0.31 (2H, m), 0.38-0.43 (2H, m), 1.36-1.47(1H, m), 1.37 (3H, d, J=6.83 Hz), 1.89-1.98 (1H, m), 2.04-2.11 (2H, m),2.27-2.59 (3H, m), 2.65 (2H, d, J=7.32 Hz), 2.81-2.88 (1H, m), 3.14-3.19(1H, m), 7.20-7.34 (5H, m).

Reference Example 3

(3R)-3-(N-t-Butoxycarbonyl-N-cyclopropyl-aminomethyl)-1-[(R)-phenylethyl]pyrrolidine

To a solution of 1.63 g (6.68 mmol) of(3R)-3-(N-cyclopropylaminomethyl)-1-[(R)-phenylethyl]pyrrolidine in 30ml of dichloromethane were added 1.75 g (8 mol) of di-t-butyldicarbonate, 8 ml of triethylamine, and 10 mg of4-dimethylaminopyridine, followed by stirring at room temperature for 20minutes. The solvent was evaporated, and the residue was purified bysilica gel column chromatography to give 2.2 g (96%) of the titlecompound from a 3% methanolchloroform eluate.

¹H-NMR (CDCl₃) δ ppm: 0.53-0.58 (2H, m), 0.70-0.74 (2H, m), 1.37 (3H, d,J=6.35 Hz), 1.44 (9H, s), 1.85-1.94 (1H, m), 2.13-2.18 (1H, m),2.41-2.64 (4H, m), 2.78-2.82 (1H, m), 3.14-3.25 (4H, m), 7.22-7.33 (5H,m).

Reference Example 4

(3R)-3-(N-t-Butoxycarbonyl-N-cyclopropylaminomethyl)pyrrolidine

To a solution of 1.7 g (4.9 mmol) of(3R)-N-t-butoxycarbonyl-N-cyclopropylaminomethyl-1-[(1R)-phenylethyl]pyrrolidinein 50 ml of ethanol was added 1.7 g of 10% palladium-on-carbon.Catalytic hydrogenation was conducted under a 4 atom of hydrogenatmosphere, while the reaction vessel was heated by an irradiation witha tungsten lamp. The catalyst was removed by filtration, and the solventwas removed from the filtrate by evaporation to give 1.2 g (100%) of thetitle compound.

¹H-NMR (CDCl₃) δ ppm: 0.60 (2H, brs), 0.75-0.85 (2H, m), 1.96 (9H, s),1.72-1.85 (1H, m), 2.10-2.20 (1H, m), 2.45-2.54 (1H, m), 2.65-2.79 (1H,m), 2.94-3.03 (1H, m), 3.21-3.51 (5H, m).

Example 1

7-[3-(R)-Cyclopropylaminomethyl-1-pyrrolidinyl]-6-fluoro-1-[(1R,2S)-2-fluorocyclopropyl]-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicAcid

To a solution of 690 mg (2 mmol) of6,7-difluoro-1-[(1R,2S)-2-fluorocyclopropyl]-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid BF₂ chelate in 8 ml of dimethyl sulfoxide were added 960 mg (4mmol) of (3R)-3-(N-t-butoxycarbonyl-N-cyclopropylaminomethyl)pyrrolidineand 1 ml of triethylamine, and the mixture was stirred at roomtemperature for 170 hours. Triethylamine was removed by evaporation, and10 ml of water was added to the residue, followed by stirring at roomtemperature for 15 minutes. The precipitated crystals were washed withwater and collected by filtration. The crystals were dissolved in 100 mlof a 4:1 mixture of ethanol and water, and 10 ml of triethylamine wasadded thereto, followed by refluxing for 3 hours. The solvent wasevaporated, and 100 ml of chloroform was added to the residue. Themixture was washed with two 30 ml portions of 10% citric acid aqueoussolution, and dried over magnesium sulfate. The solvent was evaporated,and 10 ml of concentrated hydrochloric acid was added to the residue.The mixture was stirred at room temperature for 5 minutes, washed withtwo 10 ml portions of chloroform, adjusted to a pH of 7.3 with a 20%sodium hydroxide aqueous solution, and extracted with three 80 mlportions of chloroform. The extract was dried over sodium sulfate, andthe solvent was evaporated. The residue was purified by preparative thinlayer chromatography (TLC) (developed with the lower layer of a mixtureof chloroform:methanol:water=7:3:1) to give 181 mg (22%) of a crudeproduct. Recrystallization from ethanoldiethyl ether gave 100 mg of thetitle compound.

¹H-NMR (0.1N-NaOD) δ ppm: 0.30-0.36 (2H, m), 0.41-0.50 (2H, m),1.04-1.20 (1H, m), 1.42-1.65 (2H, m), 2.00-2.17 (2H, m), 2.28-2.46 (1H,m), 2.36 (3H, s), 2.63-2.75 (2H, m), 3.19-3.35 (3H, m), 3.54-3.68 (1H,m), 3.96-4.04 (1H, m), 4.99-5.07 (0.5H, m), 7.61 (1H, d, J=14.16 Hz),8.42 (1H, s).

Elementary analysis for C₂₂H₂₅F₂N₃O₃·0.25H₂O: Calcd. (%): C 62.62; H6.09; N 9.69; Found (%): C 62.87; H 6.11; N 9.83; Melting point:163-164° C.

Example 2

5-Amino-7-[3-(R)-(N-cyclopropylaminomethyl)-1-pyrrolidinyl]-6-fluoro-1-[(1R,2S)-2-fluorocyclopropyl]-1,4-dihydro-8-methoxy-4-oxocquinoline-3-carboxylicAcid

To a solution of 328 mg (1 mmol) of5-amino-6,7-difluoro-1-[(2S)-fluoro-(1R)-cyclopropyl]-1,4-dihydro-8-methoxy-4-oxoquinoline-3-carboxylicacid in 10 ml of dimethyl sulfoxide were added 360 mg (1.5 mmol) of(3R)-3-(N-t-butoxycarbonyl-N-cyclopropylaminomethyl)pyrrolidine and 3 mlof triethylamine, and the mixture was heated at 100° C. for 15 hours.The solvent was evaporated, and 50 ml of chloroform was added to theresidue. The chloroform solution was washed with two 20 ml portions of a10% citric acid aqueous solution and dried over sodium sulfate, and thesolvent was evaporated. To the residue was added 5 ml of concentratedhydrochloric acid, followed by stirring at room temperature for 5minutes. The reaction mixture was washed with two 20 ml portions ofchloroform. The hydrochloric acid solution was adjusted to a pH of 7.3with a 20% sodium hydroxide aqueous solution and extracted with three 80ml portions of chloroform. The extract was dried over sodium sulfate,and the solvent was evaporated. The residue was purified by preparativeTLC (developed with the lower layer of a mixture ofchloroform:methanol:water=7:3:1) to obtain a crude compound.Recrystallization from diethyl ether yielded 215 mg (48%) of the titlecompound.

¹H-NMR (0.1N-NaOD) δ ppm: 0.33 (2H, brs), 0.46-0.48 (2H, m), 1.17-1.27(1H, m), 1.34-1.47 (1H, m), 1.57-1.59 (1H, m), 2.08-2.14 (2H, m),2.39-2.43 (1H, m), 2.72 (2H, brs), 3.34-3.35 (1H, m), 3.43 (3H, 2s),3.56-3.65 (2H, m), 3.86-3.89 (1H, m), 5.02 (0.5H, brs), 8.21 (1H, 2s).

Elementary analysis for C₁₉H₂₀F₂N₄O₄·0.25H₂O: Calcd. (%): 58.48; H 5.86;N 11.97; Found (%): 53.34; H 5.90; N 12.37; Melting point: 154-156° C.(with decomposition)

Example 3

5-Amino-7-[(3R)-N-cyclopropylaminomethyl-1-pyrrolidinyl]-6-fluoro-1-[(1R,2S)-2-fluorocyclopropyl]-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicAcid Hydrochloride

To a solution of 2.00 g (6.4 mmol) of5-amino-6,7-difluoro-1-[(2S)-fluoro-(1R)-cyclopropyl]-1,4-dihydro-8-methyl-4-oxoquinoline-3-carboxylicacid in 10 ml of dimethyl sulfoxide were added 2.32 g (9.6 mmol) of(3R)-N-t-butoxycarbonyl-N-cyclopropylaminomethylpyrrolidine and 30 ml oftriethylamine, and the mixture was heated at 120° C. for 5 days. Thesolvent was evaporated, and to the residue was added 10 ml ofconcentrated hydrochloric acid, followed by stirring at room temperaturefor 15 minutes. The reaction mixture was washed with two 300 ml portionsof chloroform. The hydrochloric acid solution was adjusted to a pH of7.3 with a 20% sodium hydroxide aqueous solution and extracted withthree 200 ml portions of chloroform. The extract was dried over sodiumsulfate, and the solvent was evaporated. The residue was purified bypreparative TLC (developed with the lower layer of a mixture ofchloroform:methanol:water=7:3:1), 10 ml of 1N hydrochloric acid wasadded to the crude product, and the solvent was evaporated.Recrystallization from ethanol-diethyl ether yielded 1.05 g (31%) of thetitle compound.

¹H-NMR (0.1N NaOD-D₂O) δ ppm: 0.34 (1H, brs), 0.47 (1H, brs), 1.03-1.16(1H, m), 1.42-1.61 (2H, m), 2.04-2.80 (6H, m), 3.25-3.42 (3H, m),3.66-3.74 (1H, m), 3.88-3.97 (1H, m), 8.26 (1H, s )

Elementary analysis for C₂₃H₂₉F₂N₄O₃·HCl·2.5H₂O·0.25EtOH: Calcd. (%): C51.82; H 6.47; N 10.74; Found (%): C 51.94; H 5.91; N 10.20; Meltingpoint: 145-149° C.

The antimicrobial activity of the compounds obtained in Examples 1 to 3was examined in accordance with the standard method specified by theJapan Chemotherapeutic Society. The resulting antimicrobial spectra areshown in Table 1 below.

TABLE 1 Antimicrobial Spectra (MIC: μg/ml) Test Microorganism Example 1Example 2 Example 3 E. coli, NIHJ ≦0.003 0.006 0.006 S. flexneli, 2A5503 0.006 0.013 0.006 Pr. vulgaris, 08601 0.006 0.10 0.05 Pr.mirabilis, IFO-3849 0.025 0.20 0.10 Ser. marcescens, 10100 0.10 0.390.20 Ps. aeruginosa, 32104 0.20 0.78 0.39 Ps. aeruginosa, 32121 0.100.78 0.20 Ps. maltophilia, IID-1275 0.05 0.20 0.10 S. aureus, 209P≦0.003 ≦0.003 ≦0.003 S. epidermidis, 56500 0.013 0.013 0.006 Str.pyrogenes, G-36 0.013 0.025 0.013 Str. faecalis, ATCC-19433 0.025 0.100.05 S. aureaus, 870307 0.025 0.05 0.025

What is claimed is:
 1. A compound represented by the formula (I) or asalt thereof:

wherein R¹ represents a substituted cyclic alkyl group having 3 to 6carbon atoms; R² represents a hydrogcn atom, an amino group, a hydroxylgroup, a thiol group, a halogenomethyl group, an alkyl group having 1 to6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynylgroup having 2 to 6 carbon atoms, or an alkoxyl group having 1 to 6carbon atoms, and wherein said amino group may have at least onesubstituent selected from the group consisting of a formyl group, analkyl group having 1 to 6 carbon atoms and an acyl group having 2 to 5carbon atoms; R³ represents an amino group, a halogenomcthyl group, ahalogenomethoxyl group, an alkenyl group having 2 to 6 carbon atoms, oran alkynyl group having 2 to 6 carbon atoms, and wherein said aminogroup may have at least one substituent selected from the groupconsisting of a formyl group, an alkyl group having 1 to 6 carbon atomsand an acyl group having 2 to 6 carbon atoms; R⁴ represents a hydrogenatom or an alkyl group having 1 to 6 carbon atoms, and wherein saidalkyl group may have at least one substituent selected from the groupconsisting of a hydroxyl group, a halogen atom, an alkylthio grouphaving 1 to 6 carbon atoms and an alkyloxyl group having 1 to 6 carbonatoms; R⁵ represents a cyclic alkyl group having 3 to 6 carbon atoms; Xrepresents a halogen atom or a hydrogen atom; and Y represents ahydrogen atom, a phenyl group, an acetoxymethyl group, apivaloyloxymethyl group, an ethoxymethyl group, a choline group, adimethylaminoethyl group, a 5-indanyl group, a phthalidinyl group, a5-alkyl-2-oxo-1,3-dioxol-4-ylmethyl group, a 3-acetoxy-2-oxobutyl group,an alkyl group having 1 to 6 carbon atoms, an alkoxymethyl group having2 to 7 carbon atoms, or a phenylalkyl group having 1 to 6 carbon atomsin the alkyl moiety thereof.
 2. The compound according to claim 1,wherein R¹ is a 2-halogenocyclopropyl group or a salt thereof.
 3. Thecompound according to claim 1, wherein R¹ is a1,2-cis-2-halogenocyclopropyl group or a salt thereof.
 4. The compoundaccording to any one of claims 1 to 3, wherein R¹ is a substantiallystereochemically pure substituent or a salt thereof.
 5. The compoundaccording to claim 4, wherein R¹ is a (1R,2S)-2-halogenocyclopropylgroup or a salt thereof.
 6. The compound according to claim 2, 3, or 5,wherein R¹ is a fluorocyclopropyl group or a salt thereof.
 7. Thecompound according to claim 6, wherein the compound is a substantiallystereochemically pure compound or a salt thereof.
 8. An antimicrobialcomposition comprising as an active ingredient, a compound according toclaim 1 or a salt thereof, and a pharmaceutically acceptable carrier.